Locking the Knees
I’ve been taking a variety of different Yoga classes in different styles lately, exploring what’s out there. It’s been great. With an open mind, you can always learn something new.
But not all Yoga teachers get everything right – at least not when it comes to biomechanics and safety. For instance, a surprising number of my new teachers over the past few months have instructed me (sometimes repeatedly when I don’t follow directions) to “lock” my knees in various asanas.
Locking the knee is unnecessary and potentially leads to injury in the long run.
What does it mean to lock the knee?
Locking the knee maximally extends it, transforming it into a mechanically rigid structure that maintains a straight leg. Flexion loosens the knee by unlocking the bracing structures, including retraction of the menisci, the shock absorbers to each side of the joint capsule.
Some people fully extend their knees whenever they stand still – at least one leg or the other – to improve stability and take the work off of the major muscles.
What’s the possible damage?
Locking the knee places body weight onto the joint in such a way that it forces the joint slightly out of place. The effect is magnified by placing the entire weight of the body onto one leg as in some Yoga asanas.
It puts damaging mechanical forces onto the joint cartilage including the menisci. The long-term result is cartilage degeneration and arthritis.
Locking the knees can also cause the pelvis to tilt forward which stresses the hip joints and disturbs posture throughout the spine.
Is there a test for those at greatest risk?
Yes. Some of us (and that includes me) have a greater tendency towards a hyperextendable knee joint with subsequent development of the cascade of degeneration, pain, and arthritis. Hyperextension of the knee occurs when the tibia glides on the femur excessively so that the joint moves past 180 degrees – past a straight line.
Test: Sit up straight in Dandasasana. The knees should not be externally rotated and the feet should be relaxed with no flexion at the ankle joint. Contract the quadriceps muscles. If the heel rises off the floor, then it’s likely you have a hyperextending knee joint.
What can you do to keep from hyperextending the knee?
Maintain awareness – all the time. That means when standing in line at the grocery store and stirring the soup on the stove as well as when on the mat. For some, locking the knees into hyperextension is a firmly ingrained habit, one that can be conquered with attention. I always try to do my best with this throughout my day, which is probably why I found it so frustrating that during class, when my mind is most aware of my posture, I’d been repeatedly told to do what I know is not best for me (given as an order without space for dialogue).
When instructed to “lock the knee” during Yoga sessions, extend the knee but don’t push it into a locked position. Then contract the quadriceps, the thigh muscles. Contracting the intrinsic muscles of the foot can help a little, too. Some people may benefit from wearing a knee brace.
Over the long-term, work on strengthening the quadriceps with utkatasana, keeping the thighs parallel to the floor for as long as possible with each attempt.
Bottom Line: While it may be particularly damaging for those of us with a tendency to hyperextend, locking the knee joint is not good for anybody and it’s unnecessary in Yoga.
Kujala UM, Osterman K, Kvist M, Aalto T, Friberg O. Factors predisposing to patellar chondropathy and patellar apicitis in athletes. Int Orthop. 1986;10(3):195-200.
Teran-Yengle P, Birkhofer R, Weber MA, Patton K, Thatcher E, Yack HJ. Efficacy of gait training with real-time biofeedback in correcting knee hyperextension patterns in young women. J Orthop Sports Phys Ther. 2011 Dec;41(12):948-52. Epub 2011 Oct 25.